One of the largest-ever conferences on the health effects of smoking will exploit damaging revelations about industry "dirty tricks".

The 11th World Conference on Tobacco Or Health opens in Chicago on Sunday and is expected to continue an onslaught on the world's big tobacco firms.

The industry has been hit in recent days by claims that it used underhand tactics to blunt the World Health Organisation's (WHO) global anti-smoking drive.

The firms have also been accused of combining their forces in a secret project to spread disinformation about the links between smoking and poor health.

'Dirty tricks' denial

Tobacco bosses have denied that their actions amounted to "dirty tricks".

The conference is expected to include the unveiling of new research on the health effects of smoking and latest smoking trends.

US Surgeon General David Satcher will present his strategy on smoking reduction, which will combine regulation, education and health measures in one package.

An estimated 4,500 health professionals are expected to attend the conference.

The event comes in the build-up to the start of negotiations about an international framework on tobacco control.

Worldwide ban mooted

Discussions start in October on the global treaty, which could see a worldwide ban on tobacco advertising.

WHO director-general Dr Gro Harlem Brundtland and former US Surgeon General C. Everett Koop are honorary chairmen of the conference.

Dr Brundtland has been urged to take action against the tobacco firms following her organisation's critical report.

It accused the tobacco firms of "placing" representatives inside the WHO to report back on anti-smoking activities.

Clive Bates, director of the UK anti-smoking group Action on Smoking and Health, said: "WHO must now follow up this hard-hitting report with determined action to stop the industry in its tracks.

"The Director-General, Dr Brundtland, should write to the chief executives at BAT and Philip Morris, asking them to give written guarantees that their underhand tactics will not continue into the future."